Practice Question

1.State the role of a lens

A lens forms an image by refracting (bending) light rays.

2. Describe the difference in appearance of a convex and concave lens.

A convex lens bends outwards in the middle section, whilst a concave lens bends inwards at the middle section. 

3. Define the term focal length

The distance between the centre of the lens and the principal focus is known as the focal length.

4. Describe what happens to light rays when they pass through a convex lens

A convex lens will bring parallel rays of light to a focus at a point called the principal focus.

5. Describe what happens to light rays when they pass through a concave lens.

In a concave or diverging lens, the light rays will spread out.